forked from skynetservices/skydns
/
main.go
237 lines (207 loc) · 7.05 KB
/
main.go
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// Copyright (c) 2014 The SkyDNS Authors. All rights reserved.
// Use of this source code is governed by The MIT License (MIT) that can be
// found in the LICENSE file.
package main
import (
"crypto/tls"
"crypto/x509"
"encoding/json"
"flag"
"fmt"
"io/ioutil"
"log"
"math/rand"
"net"
"net/http"
"os"
"strconv"
"strings"
"time"
backendetcd "github.com/skynetservices/skydns/backends/etcd"
"github.com/skynetservices/skydns/metrics"
"github.com/skynetservices/skydns/msg"
"github.com/skynetservices/skydns/server"
etcd "github.com/coreos/etcd/client"
"github.com/miekg/dns"
"golang.org/x/net/context"
)
var (
tlskey = ""
tlspem = ""
cacert = ""
config = &server.Config{ReadTimeout: 0, Domain: "", DnsAddr: "", DNSSEC: ""}
nameserver = ""
machine = ""
stub = false
ctx = context.Background()
)
func env(key, def string) string {
if x := os.Getenv(key); x != "" {
return x
}
return def
}
func boolEnv(key string, def bool) bool {
if x := os.Getenv(key); x != "" {
if v, err := strconv.ParseBool(x); err == nil {
return v
}
}
return def
}
func init() {
flag.StringVar(&config.Domain, "domain", env("SKYDNS_DOMAIN", "skydns.local."), "domain to anchor requests to (SKYDNS_DOMAIN)")
flag.StringVar(&config.DnsAddr, "addr", env("SKYDNS_ADDR", "127.0.0.1:53"), "ip:port to bind to (SKYDNS_ADDR)")
flag.StringVar(&nameserver, "nameservers", env("SKYDNS_NAMESERVERS", ""), "nameserver address(es) to forward (non-local) queries to e.g. 8.8.8.8:53,8.8.4.4:53")
flag.BoolVar(&config.NoRec, "no-rec", false, "do not provide a recursive service")
flag.StringVar(&machine, "machines", env("ETCD_MACHINES", "http://127.0.0.1:2379"), "machine address(es) running etcd")
flag.StringVar(&config.DNSSEC, "dnssec", "", "basename of DNSSEC key file e.q. Kskydns.local.+005+38250")
flag.StringVar(&config.Local, "local", "", "optional unique value for this skydns instance")
flag.StringVar(&tlskey, "tls-key", env("ETCD_TLSKEY", ""), "TLS Private Key path")
flag.StringVar(&tlspem, "tls-pem", env("ETCD_TLSPEM", ""), "X509 Certificate")
flag.StringVar(&cacert, "ca-cert", env("ETCD_CACERT", ""), "CA Certificate")
flag.DurationVar(&config.ReadTimeout, "rtimeout", 2*time.Second, "read timeout")
flag.BoolVar(&config.RoundRobin, "round-robin", true, "round robin A/AAAA replies")
flag.BoolVar(&config.NSRotate, "ns-rotate", true, "round robin selection of nameservers from among those listed")
flag.BoolVar(&stub, "stubzones", false, "support stub zones")
flag.BoolVar(&config.Verbose, "verbose", false, "log queries")
flag.BoolVar(&config.Systemd, "systemd", boolEnv("SKYDNS_SYSTEMD", false), "bind to socket(s) activated by systemd (ignore -addr)")
// TTl
// Minttl
flag.StringVar(&config.Hostmaster, "hostmaster", "hostmaster@skydns.local.", "hostmaster email address to use")
flag.IntVar(&config.SCache, "scache", server.SCacheCapacity, "capacity of the signature cache")
flag.IntVar(&config.RCache, "rcache", 0, "capacity of the response cache") // default to 0 for now
flag.IntVar(&config.RCacheTtl, "rcache-ttl", server.RCacheTtl, "TTL of the response cache")
flag.StringVar(&msg.PathPrefix, "path-prefix", env("SKYDNS_PATH_PREFIX", "skydns"), "backend(etcd) path prefix, default: skydns")
}
func main() {
flag.Parse()
machines := strings.Split(machine, ",")
client, err := newEtcdClient(machines, tlspem, tlskey, cacert)
if err != nil {
panic(err)
}
if nameserver != "" {
for _, hostPort := range strings.Split(nameserver, ",") {
if err := validateHostPort(hostPort); err != nil {
log.Fatalf("skydns: nameserver is invalid: %s", err)
}
config.Nameservers = append(config.Nameservers, hostPort)
}
}
if err := validateHostPort(config.DnsAddr); err != nil {
log.Fatalf("skydns: addr is invalid: %s", err)
}
if err := loadConfig(client, config); err != nil {
log.Fatalf("skydns: %s", err)
}
if err := server.SetDefaults(config); err != nil {
log.Fatalf("skydns: defaults could not be set from /etc/resolv.conf: %v", err)
}
if config.Local != "" {
config.Local = dns.Fqdn(config.Local)
}
backend := backendetcd.NewBackend(client, ctx, &backendetcd.Config{
Ttl: config.Ttl,
Priority: config.Priority,
})
s := server.New(backend, config)
if stub {
s.UpdateStubZones()
go func() {
duration := 1 * time.Second
var watcher etcd.Watcher
watcher = client.Watcher(msg.Path(config.Domain)+"/dns/stub/", &etcd.WatcherOptions{AfterIndex: 0, Recursive: true})
for {
_, err := watcher.Next(ctx)
if err != nil {
//
log.Printf("skydns: stubzone update failed, sleeping %s + ~3s", duration)
time.Sleep(duration + (time.Duration(rand.Float32() * 3e9))) // Add some random.
duration *= 2
if duration > 32*time.Second {
duration = 32 * time.Second
}
} else {
s.UpdateStubZones()
log.Printf("skydns: stubzone update")
duration = 1 * time.Second // reset
}
}
}()
}
if err := metrics.Metrics(); err != nil {
log.Fatalf("skydns: %s", err)
} else {
log.Printf("skydns: metrics enabled on :%s%s", metrics.Port, metrics.Path)
}
if err := s.Run(); err != nil {
log.Fatalf("skydns: %s", err)
}
}
func loadConfig(client etcd.KeysAPI, config *server.Config) error {
// Override what isn't set yet from the command line.
configPath := "/" + msg.PathPrefix + "/config"
resp, err := client.Get(ctx, configPath, nil)
if err != nil {
log.Printf("skydns: falling back to default configuration, could not read from etcd: %s", err)
return nil
}
if err := json.Unmarshal([]byte(resp.Node.Value), config); err != nil {
return fmt.Errorf("failed to unmarshal config: %s", err.Error())
}
return nil
}
func validateHostPort(hostPort string) error {
host, port, err := net.SplitHostPort(hostPort)
if err != nil {
return err
}
if ip := net.ParseIP(host); ip == nil {
return fmt.Errorf("bad IP address: %s", host)
}
if p, _ := strconv.Atoi(port); p < 1 || p > 65535 {
return fmt.Errorf("bad port number %s", port)
}
return nil
}
func newEtcdClient(machines []string, tlsCert, tlsKey, tlsCACert string) (etcd.KeysAPI, error) {
etcdCfg := etcd.Config{
Endpoints: machines,
Transport: newHTTPSTransport(tlsCert, tlsKey, tlsCACert),
}
cli, err := etcd.New(etcdCfg)
if err != nil {
return nil, err
}
return etcd.NewKeysAPI(cli), nil
}
func newHTTPSTransport(tlsCertFile, tlsKeyFile, tlsCACertFile string) etcd.CancelableTransport {
var cc *tls.Config = nil
if tlsCertFile != "" && tlsKeyFile != "" {
var rpool *x509.CertPool
if tlsCACertFile != "" {
if pemBytes, err := ioutil.ReadFile(tlsCACertFile); err == nil {
rpool = x509.NewCertPool()
rpool.AppendCertsFromPEM(pemBytes)
}
}
if tlsCert, err := tls.LoadX509KeyPair(tlsCertFile, tlsKeyFile); err == nil {
cc = &tls.Config{
RootCAs: rpool,
Certificates: []tls.Certificate{tlsCert},
InsecureSkipVerify: true,
}
}
}
tr := &http.Transport{
Proxy: http.ProxyFromEnvironment,
Dial: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
}).Dial,
TLSHandshakeTimeout: 10 * time.Second,
TLSClientConfig: cc,
}
return tr
}